CN115074735A - Novel nitrogen-free fluorine-free environment-friendly tin stripping liquid - Google Patents

Abstract

The invention relates to a tin stripping liquid, in particular to a nitrogen-free and fluorine-free environment-friendly tin stripping liquid. The invention provides an online installation of a rotary ceramic membrane dynamic cross-flow filtration equipment to recover metastannic acid, and can also replace the process of manufacturing and processing metastannic acid materials by reacting nitric acid and tin ingot in industry, and the tin stripping filtrate is circulated Recycling achieves the effect of turning waste into treasure, and the cleaning wastewater can be directly discharged. At the same time, there is no irritating and toxic nitrogen dioxide gas generated in the workshop during the tin stripping process, that is, a good working environment without yellow smoke and volatile acid mist, with high efficiency and high efficiency. The advantages of output, no corrosion of epoxy resin surface and small corrosion to copper base surface, etc., are especially suitable for stripping tin liquid for HDI high-precision circuit board manufacturing. By adopting the above scheme, a new type of tin stripping liquid has the advantages of high efficiency, high output, no corrosion of epoxy resin surface and little corrosion to copper base surface.

Description

A new type of nitrogen-free and fluorine-free environmentally friendly tin stripping liquid

technical field

The invention relates to a tin stripping liquid, in particular to a nitrogen-free and fluorine-free environment-friendly tin stripping liquid.

Background technique

The resist layer required for circuit protection in the process of PCB circuit board electroplating is pure tin using nitric acid type tin stripping liquid. The tin stripping process produces ammonia nitrogen, total nitrogen, fluoride and other harmful substances, and the generated wastewater needs denitrification treatment, which is costly.

SUMMARY OF THE INVENTION

The present invention overcomes the problems existing in the prior art, and provides a method to replace the nitric acid and ferric nitrate in the traditional nitric acid stripping tin solution by the action of an organic acid or an inorganic acid and an oxidizing agent, to strip the pure tin layer of PCB pattern electroplating and convert it into a metastannic acid material , At the same time, the tin-copper alloy layer IMC (including Cu6Sn5 and Cu3Sn) is peeled off together to form metastannic acid material, which fully meets the production quality of tin stripping in the PCB process and conforms to the national environmental protection policy of prohibiting the emission of nitrite and nitrate carcinogens. It is required that there is no irritating odor in the process of stripping tin, that is, a good working environment without yellow smoke and acid mist, and there is no bite corrosion phenomenon on PCB hole copper and surface copper. The equipment can recover metastannic acid, and the tin stripping filtrate can be recycled and reused to achieve the effect of turning waste into treasure. The cleaning wastewater can be directly discharged, without the need for denitrification treatment like traditional nitric acid-type tin stripping liquid wastewater, with high efficiency, high output, It has the advantages of not corroding the epoxy resin surface and small corrosion to the copper base surface, and is especially suitable for the stripping liquid for the manufacture of HDI high-precision circuit boards.

To achieve the above object, the present invention adopts the following technical solutions: a novel nitrogen-free, fluorine-free environment-friendly tin stripping liquid, characterized in that: the stripping liquid contains organic acid or inorganic acid, oxidant, tin-copper alloy layer stripping, stabilizer , bank protection agent and wetting agent, wherein the content of organic acid or inorganic acid is 300-800g/L, the content of oxidant is 50-150g/L, the content of tin-copper alloy layer stripping agent is 50-100g/L, and the content of stabilizer is 50-100g/L. The content of the water is 10-40g/L, the content of the bank protection agent is 1-10g/L, and the content of the wetting agent is 3-20g/L.

By adopting the above scheme, there is no need to change the existing nitric acid type tin stripping liquid equipment, there is no nitric acid, fluorine, iron and other elements in the tin stripping liquid, and there is no stimulation of the production of toxic nitrogen dioxide gas and volatile acid mist during the tin stripping process. Working environment, online installation of rotating ceramic membrane dynamic cross-flow filtration equipment to recover metastannic acid, which can also replace the process of manufacturing and processing metastannic acid materials by reacting nitric acid and tin ingot in the industry, and the tin stripping filtrate can be recycled and reused To achieve the effect of turning waste into treasure, the cleaning wastewater can be directly discharged, and there is no need for denitrification treatment like the traditional nitric acid-type tin stripping liquid wastewater.

A further arrangement of the present invention is: the organic acid is one or more of glycolic acid, alkylsulfonic acid, malic acid, acrylic acid, oxalic acid, dicarboxylic acid, diacetic acid, formic acid, and lactic acid, or an inorganic acid The acid is one or both of sulfuric acid or hydrochloric acid.

A further arrangement of the present invention is that the bank protection agent is one or more of polyvinylpyrrolidone, 2-methylimidazole, benzotriazole, methylbenzotriazole and 2-mercaptobenzimidazole.

The further arrangement of the present invention is: the stabilizer is sodium gluconate, sodium tungstate, cerium sulfate, thiourea, vitamin C, allylurea, 1,3-dimethylurea, phenylurea, α,α One or more of bipyridine, thiazole and imidazole.

A further arrangement of the present invention is: the sizing agent is polyethylene glycol 1000, polyethylene glycol 6000, ethylene glycol, diethylene glycol, acetylene glycol, sorbitol, stearyl alcohol, hexadecanol, polyethylene glycol One or more of Alcohol 8000.

A further arrangement of the present invention is: the oxidizing agent is one of sodium persulfate, potassium persulfate, potassium peroxysulfate, sodium chlorate, potassium perchlorate, hydrogen peroxide, dimethyl sulfoxide, peracetic acid or variety.

A further arrangement of the present invention is: the tin-copper alloy layer stripping agent is 1.4 butanediol, ethylene glycol monobutyl ether, 2.4.6 tricarboxyphenol, 2,6-dicarboxy-4-ethylphenol , one or more of ethylene glycol monomethyl ether, 5-carboxy-1-naphthol, dipropylene glycol monomethyl ether, and 4-carboxyphenol.

Description of drawings

Fig. 1 is the effect diagram of embodiment 1 after the tin-plated plate is soaked in nitrogen-free, fluorine-free environment-friendly tin stripping solution;

Fig. 2 is the effect diagram after the tin plate of embodiment 2 is soaked in nitrogen-free and fluorine-free environment-friendly tin stripping solution;

Figure 3 is a comparison experiment test chart of PCB substrate and copper without corrosion.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

Example 1

A new type of nitrogen-free, fluorine-free and environmentally friendly tin stripping liquid, including alkyl sulfonic acid, potassium hydrogen peroxide, allyl urea, 1.4-butanediol, 2-methylimidazole and ethylene glycol, wherein alkyl The content of sulfonic acid is 800g/L, the content of potassium hydrogen peroxysulfate is 150g/L, the content of allyl urea is 40g/L, the content of 1.4 butanediol is 100g/L, the content of 2-methylimidazole is 10g/L and The ethylene glycol content was 20 g/L.

The stripping liquid of the above formula passed the beaker test,

Test process: tin plate → soaking in the above-mentioned non-nitrogen and fluorine-free environmentally friendly tin stripping solution → washing;

Recording time: 90 seconds tin stripping;

Tin stripping conditions: The tin thickness of the tin plate is 7.56um, the acid equivalent is 6.4N, and the temperature is 45℃.

After the above conditions and processes, all the tin on the tin plate is dissolved by the tin stripping liquid.

Embodiment 2

A new type of nitrogen-free, fluorine-free and environmentally friendly tin stripping liquid, including alkyl sulfonic acid, potassium hydrogen peroxide, allyl urea, 1.4-butanediol, 2-methylimidazole and ethylene glycol, wherein alkyl The content of sulfonic acid is 560g/L, the content of potassium hydrogen peroxide is 50g/L, the content of allyl urea is 10g/L, the content of 1.4 butanediol is 50g/L, and the content of 2-methylimidazole is 1.0g/L and ethylene glycol content of 3.0g/L.

The stripping liquid of the above formula passed the beaker test,

Test process: tin plate → immersion in the above configuration of nitrogen-free and fluorine-free environmentally friendly tin stripping solution → water washing;

Recording time: 120 seconds for tin stripping;

Tin stripping conditions: The tin thickness of the tin plate is 7.56um, the acid equivalent is 4.6N, and the temperature is 45℃.

After the above conditions and processes, all the tin on the tin plate is dissolved by the tin stripping liquid.

In addition, we can also see from Fig. 3 that the nitrogen-free and fluorine-free environment-friendly tin stripping solution of the present invention is non-corrosive to both the PCB substrate and copper. In Fig. 3, A is the PCB substrate, and B is the PCB substrate. After passing through the nitrogen-free and fluorine-free environment-friendly tin stripping liquid of the present invention, it is visually displayed through a high-footed 100-times microscope that no texture of the PCB substrate is exposed. D in FIG. 3 is a view of the substrate of C in FIG. 3 after being immersed in the nitrogen-free, fluorine-free environment-friendly tin stripping solution of the present invention, and the thickness of copper in C and D in FIG. 3 is basically kept unchanged by monitoring the tester, There is no change in the weight measured by the gravimetric method.

Claims (7)

1. The novel nitrogen-free and fluorine-free environment-friendly tin stripping liquid is characterized by comprising organic acid or inorganic acid, oxidant, tin-copper alloy layer stripping, stabilizer, bank protection agent and wetting agent, wherein the content of the organic acid or the inorganic acid is 560-150 g/L, the content of the oxidant is 50-150g/L, the content of the tin-copper alloy layer stripping agent is 50-100g/L, the content of the stabilizer is 10-40g/L, the content of the bank protection agent is 1-10g/L, and the content of the wetting agent is 3-20 g/L.

2. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the organic acid is one or more of glycolic acid, alkyl sulfonic acid, malic acid, acrylic acid, oxalic acid, dicarboxylic acid, diacetic acid, methane diacid and lactic acid, or the inorganic acid is one or two of sulfuric acid and hydrochloric acid.

3. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the bank protection agent is one or more of polyvinylpyrrolidone, 2-methylimidazole, benzotriazole, methylbenzotriazole and 2-mercaptobenzimidazole.

4. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the stabilizer is one or more of sodium gluconate, sodium tungstate, cerium sulfate, thiourea, vitamin C, allyl urea, 1, 3-dimethyl urea, phenylurea, alpha bipyridyl, thiazole and imidazole.

5. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the impregnating compound is one or more of polyethylene glycol 1000, polyethylene glycol 6000, ethylene glycol, diethylene glycol, alkynediol, sorbitol, octadecanol, hexadecanol and polyethylene glycol 8000.

6. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the oxidant is one or more of sodium persulfate, potassium peroxysulfate, sodium chlorate, potassium perchlorate, hydrogen peroxide, dimethyl sulfoxide and peroxyacetic acid.

7. The novel nitrogen-free fluorine-free environment-friendly tin stripping liquid as claimed in claim 1, is characterized in that: the tin-copper alloy layer stripping agent is one or more of 1.4 butanediol, ethylene glycol monobutyl ether, 2.4.6 tricarboxyphenol, 2, 6-dicarboxy-4-ethylphenol, ethylene glycol monomethyl ether, 5-carboxyl-1-naphthol, dipropylene glycol monomethyl ether and 4-carboxyphenol.

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